Abstract The proposed project will develop an innovative web-based decision aid (DA) to improve decision making for lung cancer screening (LCS) among individuals at high risk for lung cancer due to cigarette smoking. Recent National Lung Screening Trial (NLST) data demonstrated a 20% relative reduction in lung cancer mortality for low dose computed tomography screening as compared to chest X-ray among individuals at high lung cancer risk. Given that lung cancer is the leading cause of cancer death in the United States with an estimated 160,340 deaths predicted for 2012, the new data have reinvigorated interest in LCS. However, LCS carries substantial risks including a high false positive rate, over-diagnosis, adverse psychosocial consequences, and increased radiation exposure. Further, it is unknown whether LCS would reduce lung cancer mortality among individuals who smoke but do not meet NLST eligibility criteria. Therefore, there is currently no clear best choice for whether a given individual should be screened or not. Decisions about participating in LCS should be well informed and consistent with individual preferences. However, our previous data indicate that individuals who do undergo LCS rarely have a thorough understanding of the risks or benefits. To address this rapidly emerging public health challenge, this research will 1) develop a web-based decision aid (DA) to facilitate informed decision making regarding LCS in individuals at high risk for lung cancer (i.e., cigarette smokers), and 2) assess feasibility of DA administration and proposed methods for conducting a future randomized clinical trial (RCT) of DA effectiveness. The content of the DA will be based on our previous studies exploring LCS decision making and other recent research. The specific aims of the currently proposed research are: Aim 1: Develop a DA to help individuals make informed decisions about LCS that are consistent with their values and preferences. We will develop the DA based on our previously developed KEV framework and guided by previous research, including our program of LCS decision research. Aim 2: Conduct a feasibility trial of the DA among individuals at high risk of lung cancer due to heavy cigarette smoking. We will recruit participants to assess feasibility of: 1) delivering the DA intervention in a community setting, and 2) conducting research procedures and assessment tools as planned for a future RCT. Our proposed work is highly significant, as the potential risks and limitations of LCS are substantial, the benefits of screening for populations outside the NLST criteria are uncertain, and millions of Americans will be facing decisions about screening. Our work is also highly innovative, as a LCS-DA can fundamentally improve the way these decisions are made. In addition, integrating a conjoint survey instrument as part of a DA for LCS is a novel approach to facilitate informed decision making among this large, high-risk population.